Method and Apparatus for Characterizing Coal Tar in Soil

ABSTRACT

The present invention provides a method and apparatus or system for determining an amount of coal tar that can enter, and subsequently be displaced from, a given type of soil for a range of depths of the soil. The method and apparatus also provide verification of the pressure at which coal tar can be displaced from a given type of soil. In particular, the method and apparatus simulate the hydrostatic pressure that a soil sample encounters in the subsurface of the ground. Accordingly, the method and apparatus provide a relationship between the concentration of coal tar in the soil and the pressure required to displace the coal tar from the soil, which allows for an estimation of the amount of coal tar that may be displaced at a particular location or site. Further, the method and apparatus are adaptable for use in the laboratory or the field.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method and apparatus for determining anamount of coal tar that can be displaced from a given type of soil for arange of depths of the soil. More particularly, the method and apparatusof the present invention relate to development of a relationship betweenthe concentration of coal tar in the soil and the pressure required todisplace the coal tar from the soil.

2. Description of the Related Art

Manufactured gas plants (MGPs) were typically built adjacent to streams,rivers and estuaries to supply towns with an energy source in the 1800'sand continued operations until the 1960s when a network of gas pipelineswas built across the country. Many MGPs were abandoned or demolished andleft behind a large amount of waste and contamination that now pose apotential environmental problem. A byproduct of the gasification processwas “coal tar,” which is a mixture of polycyclic hydrocarbons (PAHs) andmonocyclic hydrocarbons (MAHs).

The environmental concern over the presence of coal tar as a non-aqueousphase liquid (NAPL) in the subsurface of MGP sites is a subject ofinterest to both regulators and the companies they regulate. The concernis centered over whether the NAPL is trapped or can be displaced fromthe soil into a water source. If the NAPL can be displaced from withinthe soil, it may flow vertically through an aquifer or laterally downsloping fine-grained stratigraphic units and either directly into awater source or indirectly into a water source by providing anadditional pressure that can displace the otherwise trapped NAPL.

The types and quantities of waste discharged from MGP plants thatintroduced coal tar into the environment are highly varied. Coal tarsare complex mixtures of over 10,000 organic compounds of varyingmolecular weight, functional groups and characteristics, and less than40% of these individual compounds can be quantified using common organicchemistry techniques because of the presence of pitch. See Lee, et al.Env. Sci. and Tech. 26:2110-2115 (1992). The pitch fraction of coal taris significant in that many components within pitch are consideredrelatively insoluble but still enter water to the extent of theirsolubility.

State regulations have presented challenges to field personnel who mustquickly, consistently and accurately identify, record and characterizecoal tar within a test site. The most important concern is whether acoal tar is trapped or can be displaced from a given type of soil. Thereis little information in the literature regarding the point at whichcoal tar becomes trapped in a soil. Furthermore, there is no method orsystem that would provide one of skill in the art with a way ofdetermining whether coal tar is trapped or can be displaced from a giventype of soil from a variety of locations within a site. Accordingly,those of skill in the art would benefit from a method or system for thedetermination of the amount of coal tar that can enter, and subsequentlybe displaced from, a given type of soil for a range of depths of thesoil, and verification of the pressure at which coal tar can bedisplaced from the given type of soil.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus or system fordetermining an amount of coal tar that can enter, and subsequently bedisplaced from, a given type of soil for a range of depths of the soil.The method and apparatus also provide verification of the pressure atwhich coal tar can be displaced from a given type of soil. Inparticular, the method and apparatus simulate the hydrostatic pressurethat a soil sample encounters in the subsurface of the ground.Accordingly, the method and apparatus provide a relationship between theconcentration of coal tar in the soil and the pressure required todisplace the coal tar from the soil, which allows for an estimation ofthe amount of coal tar that may be displaced at a particular location orsite. Further, the method and apparatus are adaptable for use in thelaboratory or the field.

In one embodiment, the present invention provides a method fordetermining an amount of coal tar that can enter a given type of soil ata range of soil depths at a field site, comprising: placing a soilsample free of coal tar from a site in a pressurizable chamber; fillingthe pressurizable chamber with water, thereby displacing gas from thepressurizable chamber; feeding coal tar at a first predeterminedpressure to the pressurizable chamber, thereby pressurizing the soilsample to the first predetermined pressure and displacing a portion ofthe water with the coal tar to create an amount of displaced water;measuring the amount of the displaced water to determine an amount ofcoal tar that entered the soil sample; repeating said feeding and saidmeasuring at a plurality of additional predetermined pressures toprovide a plurality of pressures and corresponding amounts of coal tarthat entered the soil sample; and correlating each of said pressures toa depth of soil at a field site to determine an amount of coal tar thatcan enter the soil at a range of soil depths at the field site.

In another embodiment, the present invention provides a method fordetermining an amount of coal tar that can be displaced from a soilsample at a range of soil depths at a field site, comprising: placing asoil sample comprising a known amount of coal tar in a pressurizablechamber; removing gas from the soil sample; feeding water at a firstpredetermined water pressure to the pressurizable chamber, therebypressurizing the soil sample to the first predetermined water pressureand displacing a portion of the coal tar from the sample to product anamount of displaced coal tar; measuring the amount of displaced coaltar; repeating said feeding water and said measuring the amount ofdisplace coal tar at a plurality of additional predetermined waterpressures, thereby generating a plurality of water pressures andcorresponding amounts of displaced coal tar; and correlating each ofsaid water pressures to a depth of soil at the field site to determinean amount of coal tar that can be displaced from the soil sample at arange of soil depths at the field site.

In another embodiment, the present invention provides an apparatus,adaptable for positioning in the laboratory or the field, fordetermining an amount of coal tar that can enter, and subsequently bedisplaced from, a given type of soil for a range of depths of the soil,comprising: a pressurizable chamber configured to hold a soil sample; atleast two reservoirs fluidly connected to said pressurizable chamber andconfigured to feed a pressurized fluid to said pressurizable chamber;and a source of controlled pressure fluidly connected to each of said atleast two reservoirs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating a method of determining an amount ofcoal tar that can enter a given type of soil, according to oneembodiment of the present invention;

FIG. 2 is a flowchart illustrating a method of determining an amount ofcoal tar that can be displaced from a given type of soil, according toanother embodiment of the present invention;

FIG. 3 is a flowchart illustrating a method of verifying that an amountof coal tar displaced from a sample from the site at a given depth isapproximately the same as the amount of coal tar displaced in accordancewith the method of FIG. 1;

FIG. 4 illustrates a hysteresis relationship between an amount of coaltar that can enter, and subsequently be displaced from, a given type ofsoil at a plurality of predetermined pressures corresponding to a rangeof depths of the soil, according to one embodiment of the presentinvention;

FIG. 5 illustrates a system for determining an amount of coal tar thatcan enter, and subsequently be displaced from, a given type of soil fora range of depths of the soil, and verifying the pressure at which coaltar can be displaced from the given type of soil, according to oneembodiment of the present invention; and

FIG. 6 is an example of a coal tar injection curve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As discussed in more detail below, the invention generally comprises amethod and apparatus or system for determining an amount of coal tarthat can enter, and subsequently be displaced from, a given type of soilfor a range of depths of the soil. The method and apparatus also provideverification of the pressure at which coal tar can be displaced from agiven type of soil. In particular, the method and apparatus simulate thehydrostatic pressure that a soil sample encounters in the subsurface ofthe ground. Accordingly, the method and apparatus provide a relationshipbetween the concentration of coal tar in the soil and the pressurerequired to displace the coal tar from the soil, which allows for anestimation of the amount of coal tar that may be displaced at aparticular location or site. Further, the method and apparatus areadaptable for use in the laboratory or the field.

The following text in connection with the Figures describes variousembodiments of the present invention. The following description,however, is not intended to limit the scope of the present invention. Itshould be appreciated that where the same numbers are used in differentfigures, these refer to the same element or structure. It should beappreciated that in the following description, the concentration of coaltar in a sample of soil is the amount of coal tar in the total voidspace within the sample and is expressed herein as percent coal tar. Theamount of coal tar entering, and subsequently displaced from, a givensample of soil is expressed herein as a change in the percentage of coaltar in the sample.

FIG. 1 is a flowchart illustrating a method of determining an amount ofcoal tar that can enter a given type of soil, according to oneembodiment of the present invention. More particularly, this methodallows for the determination of the amount of coal tar that can enter agiven type of soil by feeding coal tar into a soil sample atincrementally higher pressures. Generally, a graphical representation orcurve may be generated illustrating the relationship between the amountof coal tar that can be forced into a given soil sample and the pressurerequired to force that amount of coal tar into the sample. This curve isgenerated by obtaining the quantity of water that is pushed out of thesample under a given stress or pressure from the entering coal tar.These pressures can be related to soil depth at a field location or siteto allow the determination of the depth at which coal tar may be presentin the soil. For example, a given pressure may be required to force acertain amount of coal tar into a particular soil sample to produce agiven coal tar concentration in the soil. This pressure may be relatedto pressure experienced by the soil at a particular depth below the soilsurface at a particular field location. It may then be concluded thatsoil at or below this depth would be capable of having that same coaltar concentration or more. In addition, knowing the coal tarconcentration of a soil sample and the depth at which it was taken, thismethod can be used to determine whether the soil at that depth couldhold additional coal tar. For example, if the soil sample obtained at agiven depth contained a concentration of coal tar that was less than theconcentration of coal tar measured at a corresponding pressure using themethod of the present invention, then the soil at that depth may becapable of holding additional coal tar. It should be appreciated,however, that disruptions to the soil, either natural or man-made wouldaffect this type of analysis.

The first step 102 of the method 100 of FIG. 1 comprises placing aprepared soil sample from a field site in a pressurizable chamber. Itshould be appreciated that this soil sample should be free of coal tar,which can be verified by analytical techniques. The soil sample may beobtained from the site at depths of up to about 300 feet below thesurface. In a preferred embodiment, the sample is obtained at depths ofup to about 100 feet below the surface. The first sample is oven-driedat a temperature of about 105° C. to about 110° C. for at least 12hours, and the amount of the first sample placed into the pressurizablechamber is recorded.

It should be appreciated that the first sample may be obtained using anydevice known to one of skill in the art for obtaining soil samples. Coresampling devices that might be used to collect soil samples include, butare not limited to, gravity corers, vibracorers, piston corers or ahollow-stem auger drill with a split-spoon sampler. The method ofobtaining soil samples should be consistent to the extent that each ofthe soil samples in a sample set are obtained such that they havecomparable densities, since a variation in the density of the soilsample can create a variation in the results of the present invention.Furthermore, the temperature at which the sample may be oven dried andthe duration of drying may vary depending upon the given type of soil.The preferred temperature to oven dry the soil is from about 60° C. toabout 110° C. to avoid thermal degradation of components within thesoil.

After placing the first sample in the pressurizable chamber, the nextstep 103 comprises filling the pressurizable chamber with water, therebydisplacing gas from the pressurizable chamber. The gas is displaced byallowing the first sample to equilibrate with a positive pressure ofwater entering one end of the pressurizable chamber and a back-pressureof water entering an opposite end of the pressurizable chamber.Normally, it takes from approximately one hour to three days for thefirst sample and water to reach equilibrium. Equilibrium occurs, forexample, when there are no air bubbles exiting the system in theeffluent line of the chamber.

It should be appreciated that any method of displacing gas from thechamber may be used in the methods of the present invention. Forexample, the gas may be displaced using vacuum and replacing thedisplaced gas with water. In another example, the gas may also bedisplaced by repetitive freezing and thawing, which can be accomplishedin a freeze-drying apparatus. In another example, the sample and watercan be heated in the chamber to displace gas. Accordingly, the time todisplace gas from the first sample can vary with variation with themethod chosen.

After filling the pressurizable chamber with water, thereby displacinggas from the pressurizable chamber, the next step 104 comprises feedingcoal tar at a first predetermined pressure to the pressurizable chamberusing compressed air. The first sample is pressurized to the firstpredetermined pressure, thereby displacing the water with the coal tarto create an amount of displaced water.

It should be appreciated that any form of pressure, positive ornegative, may be used to feed coal tar into the pressurizable chamber.For example, any gas can be used to provide a positive pressureincluding, but not limited to, compressed air and inert gases such asnitrogen, argon, helium or neon. In another example, the pressure can beapplied mechanically with an apparatus such as a pump or press. Inanother example, the pressure can be negative pressure from a vacuum ifthe water vapor pulled from the first sample is trapped in a condenserfor purposes of later measuring the amount of displaced water.

After feeding coal tar at the first predetermined pressure, therebydisplacing the water with the coal tar to create an amount of displacedwater, the next step 105 is measuring the amount of displaced water byobserving a change in water level in an attached reservoir or effluentchamber. The amount of water displaced from the soil sample is equal tothe volume amount of coal tar entering the soil sample. Knowing theoven-dried weight of the soil sample allows for calculation of theconcentration of coal tar in the soil sample at the first predeterminedpressure.

It should be appreciated that the amount of displaced water can bemeasured in any manner known to one of skill in the art. For example,the amount of displaced water can be measured volumetrically orgravimetrically. Further, it should be appreciated that the sample mustreach equilibrium after applying a predetermined pressure before theamount of displaced water is measured. Equilibrium can take, forexample, from about one minute to one week. To determine whenequilibrium has been reached, the effluent chamber is monitored for thepresence of air bubbles. In addition, if the volume in the effluentchamber remains constant at the particular pressure, equilibrium hasbeen reached. It should be appreciated, however, that when performingthis procedure in the field, leachate is collected at each givenpressure noting that the system may not have reached equilibrium.Therefore, the field test is viewed as a dynamic test and providesrelative information about the pressure required to force coal tar intoa given soil sample.

The next step is repeating 106 the steps of feeding coal tar 104 andmeasuring displaced water 105 at a plurality of additional pressures toprovide a range of pressures corresponding to a range of depths of thesoil at the field site. The maximum pressure is reached when the amountof displaced water reaches an asymptotic minimum, indicating that thetotal amount of coal tar entering the sample has reached an asymptoticmaximum.

The range of pressures applied may include from about 0.01 psi to about100 psi or any range therein. In a preferred embodiment, the range ofpressures is from about 0.01 psi to about 60 psi, or any range therein.As indicated above, it should be appreciated that the pressures appliedto the samples can be a positive pressure or a negative pressure.Accordingly, if a negative pressure is used, the maximum pressure willbe limited to atmospheric pressure.

FIG. 2 is a flowchart illustrating a method of determining an amount ofcoal tar that can be displaced from a given type of soil, according toanother embodiment of the present invention. More particularly, thismethod allows for the determination of the amount of coal tar that canbe displaced from a given type of soil by displacing coal tar from asoil sample containing a maximum amount of coal tar. In essence, thismethod is the reverse of the method described in connection with FIG. 1,and the soil sample containing a maximum amount of coal tar may begenerated by the method described in connection with FIG. 1. Generally,a graphical representation or curve may be generated illustrating therelationship between the amount of coal tar that may be displaced from agiven soil sample and the pressure required to displace that amount ofcoal tar. This curve is generated by measuring the quantity of coal tarthat is pushed out of the sample under a given stress or pressure. Thecoal tar in the soil sample is displaced by feeding water into thesample at incrementally higher pressures. These pressures can also berelated to soil depth at a field location or site to allow thedetermination of the depth at which coal tar may be capable of mobilitywithin the soil. Again, it should be appreciated, however, thatdisruptions to the soil, either natural or man-made would affect such ananalysis.

As noted above, the method 200 begins with a soil sample that has amaximum amount of coal tar and may be prepared using the method ofFIG. 1. Therefore, the first step 111 in the method 200 of FIG. 2 beginswith the soil sample that is in the chamber at the end of the method 100of FIG. 1. The first step 111, therefore, is reversing the direction ofpressure on the soil sample in the pressurizable chamber to displace thecoal tar from the sample.

It should be appreciated that a relationship between the concentrationof coal tar in the soil and the pressure required to displace the coaltar from the soil can begin at any coal tar concentration. Accordingly,it is possible to start with a soil sample having a maximumconcentration of coal tar that has been prepared by another method orsimply to start with a soil sample that has any concentration of coaltar in it, such as a field sample containing coal tar. The amount ofcoal tar in the sample can be determined in the laboratory usingprocedures known to one of skill in the art including, but not limitedto, solvent extraction and gravimetric procedures. A sample from a fieldsite, however, will require displacing gas 112 from the sample in themanner discussed above before proceeding with determining an amount ofcoal tar that can be displaced from the first sample at a range ofpredetermined water pressures.

After reversing the direction of pressure on the first sample comprisinga known amount of coal tar in the pressurizable chamber and displacinggas if necessary, the next step 113 is feeding the water at a firstpredetermined pressure to the pressurizable chamber. The sample ispressurized to the first predetermined pressure, thereby displacing thecoal tar with the water to create an amount of displaced coal tar. Asdescribed above in connection with FIG. 1 and feeding coal tar underpressure, it should be appreciated that any form of pressure, positiveor negative, may be used to feed water into the pressurizable chamber.

After feeding water at the first predetermined pressure, therebydisplacing the coal tar with the water to create an amount of displacedcoal tar, the next step 114 is measuring the amount of displaced coaltar by observing a change in coal tar level in an attached reservoir.The amount of coal tar displaced from the sample is equal to the amountof water entering the sample. Knowing an oven-dried amount for thesample without coal tar allows for calculation of the amount of coal tarthat can be displaced from the sample at the first predeterminedpressure. As described above in connection with FIG. 1 and themeasurement of displaced water, it should be appreciated that the amountof displaced coal tar can also be measured in a similar manner.

The next step 115 is repeating the feeding of water 113 and themeasuring of displaced coal tar 114 at a plurality of additional waterpressures to provide a range of water pressures corresponding to a rangeof depths of the soil. The maximum pressure is reached when the amountof displaced coal tar reaches an asymptotic minimum, indicating that thetotal amount of coal tar displaced from the sample has reached anasymptotic maximum.

The range of pressures applied may include from about 0.01 psi to about100 psi or any range therein. In a preferred embodiment, the range ofpressures is from about 0.01 psi to about 60 psi, or any range therein.As indicated above, it should be appreciated that the pressures appliedto the samples can be a positive pressure or a negative pressure.Accordingly, if a negative pressure is used, the maximum pressure willbe limited to atmospheric pressure.

FIG. 3 is a flowchart illustrating a method of verifying that an amountof coal tar displaced from a sample from the site at a given depth isapproximately the same as the amount of coal tar displaced in accordancewith the method of FIG. 1. It should be appreciated that this method canbe performed using the same apparatus as the methods described inconnection with FIGS. 1 and 2.

The method 300 comprises the first step 121 of obtaining an additionalsample from a predetermined depth within a field site that contains coaltar. The next step 122 is pressurizing the sample comprising coal tar inthe chamber at a pressure approximately equivalent to a pressure at thepredetermined depth to displace leachate. The next step 123 is measuringthe amount of the displaced coal tar in the leachate, wherein thepressure at the predetermined depth is estimated using calculationsknown to one of skill in the art.

An optional step 124 of separating the components of the leachate thatcan pass through a hydrophilic filter provides for separation of coaltar components that are the most soluble in a solvent such as water inorder to, for example, identify the most likely sources of contaminationof a water supply. In a preferred embodiment, the hydrophilic filter isa paper filter. It should be appreciated that other hydrophilic filterscan be used including, but not limited to, porous glass filters.

Another optional step 125 of eluting the sample with a solvent,preferably water, provides another way to extract components of the coaltar from the sample for analysis. It should be appreciated that thechoice of solvent is dependent upon the components that are beingextracted. In a preferred embodiment, water is used to extract andidentify soluble leachate components that are most likely to contaminategroundwater. In another embodiment, dichloromethane, alcohol or methanolmay be used, for example, to extract all of the coal tar from the samplefor analysis.

The analysis of the coal tar components is provided using gaschromatography and flame ionization detection (GC/FID). It should beappreciated that any instrumentation known to one of skill in the artcan be used to analyze the components of the coal tar including, but notlimited to, gas chromatography, flame ionization detection, highpressure liquid chromatography, mass spectroscopy, UV spectroscopy,infrared spectroscopy, nuclear magnetic resonance, fluorescence, thermogravimetric analysis, calorimetery or combinations thereof.

FIG. 4 illustrates a hysteresis relationship between an amount of coaltar that can enter, and subsequently be displaced from, a given type ofsoil at a plurality of predetermined pressures corresponding to a rangeof depths of the soil, according to one embodiment of the presentinvention. The hysteresis relationship is produced using the method 100described in connection with FIG. 1 and the method 200 described inconnection with FIG. 2. It should be appreciated that the horizontalaxis is pressure; however, for the downward curve 201, the pressureincreases from the left to the right and for the upward curve 202, thepressure increases from right to left.

The method 100 described in connection with FIG. 1 is used to developthe downward curve 201, which represents an amount of coal tar that canenter a given type of soil for a range of depths of the soil. Asindicated in FIG. 4, downward curve 201 begins with the sample saturatedsuch that 100% of the void space within the sample is filled with waterdue to the displacing gas step 103 described above. Feeding the coal tarat a first predetermined pressure 104, measuring the amount of displacedwater 105, and repeating these steps 104, 105 provides the data pointsthat constitute the downward curve 201. Dashed line 204 indicates amaximum coal tar concentration where the amount of displaced waterreaches an asymptotic minimum for the increase to the maximum pressuresuch that the total amount of coal tar entering the first sample hasreached an asymptotic maximum.

The method 200 described in connection with FIG. 2 is used to developthe upward curve 202, which represents an amount of coal tar that can bedisplaced from a given type of soil for a range of depths of the soil.As indicated in FIG. 4, upward curve 202 begins with the samplecontaining the maximum coal tar concentration indicated by the dashedline 204. Feeding the water at a first predetermined water pressure 113,measuring the amount of displaced coal tar 114, and repeating thesesteps 113, 114, provides the data points that constitute upward curve202. Dashed line 203 indicates a minimum coal tar concentration suchthat the total amount of coal tar displaced from the first sample hasreached an asymptotic maximum.

The hysteresis relationship of FIG. 4 is useful in that it provides away to determine (1) whether coal tar can be displaced from a given typeof soil at a particular depth when the coal tar concentration is knownat that depth; (2) the concentration of coal tar in a given type of soilwhen the pressure required to displace the coal tar from the given typeof soil is known; (3) the maximum amount of coal tar that can enter agiven type of soil; and (4) the maximum amount of coal tar that can bedisplaced from a given type of soil. For example, from these curves, theminimum pressure at which the coal tar is at equilibrium in the soil isknown. Any pressure above this minimum pressure would force the coal tarto move in soil. In other words, soil found at a particular depthwherein the pressure on the soil is above this minimum pressure may becapable of forcing the coal tar in the soil to move. Alternatively, ifthe coal tar is bound to the soil or if the soil is at a depth whereinthe pressure is below this minimum pressure, then the coal tar would notbe expected to be mobile.

Accordingly, the hysteresis relationship illustrated in FIG. 4 providesone of skill in the art with a way of determining the amount of coal tarthat can enter, and subsequently be displaced from, a given type of soilfor a range of depths of the soil, and verifying the pressure at whichcoal tar can be displaced from the given type of soil. In particular,the hysteresis relationship illustrates a simulation of the pressurethat a sample encounters in the subsurface and provides a relationshipbetween the concentration of coal tar in the soil and the pressurerequired to displace the coal tar from the soil, and this relationshipallows for, inter alia, as described above, a determination of whethercoal tar can be displaced from the soil at a particular location on asite.

FIG. 5 illustrates a system for determining an amount of coal tar thatcan enter, and subsequently be displaced from, a given type of soil fora range of depths of the soil, and verifying the pressure at which coaltar can be displaced from the given type of soil, according to oneembodiment of the present invention. The major components of the systemare a chamber 301, a first reservoir 304 adaptable for connection to thechamber 301, a second reservoir 307 adaptable for connection to thechamber 301, a container 311 adaptable for connection to the chamber, ahydrophilic filter 316 adaptable for connection to the chamber 310 andthe container 311, and a source of controlled pressure 321. It should beappreciated that the controlled source of pressure can be a source ofpositive pressure that is connected to the first reservoir inlet 305 orthe second reservoir inlet 307. Alternatively, the source of controlledpressure 321 may be connected to the inlet 302 to the chamber 301 (notshown). Alternatively, the controlled source of pressure may be acontrolled source of negative pressure connected downstream of thechamber 301, which is discussed in more detail below.

For purposes of developing the hysteresis relationship in the embodimentof FIG. 2, the system is comprised of the chamber 301 connected to thefirst reservoir 304 and the second reservoir 307 (“the reservoirs”). Thereservoirs are adaptable for connection to the source of controlledpressure 321 and are connected to the chamber 301 by connecting firstreservoir inlet 305 to chamber inlet 302 and by connecting secondreservoir inlet 308 to chamber outlet 303, each of which are connectedusing a flexible and pressurizable tubing such as nylon braided Tygon®tubing.

Preferably, the chamber 301 is essentially a cylinder that ispressurizable up to at least 500 psi. The chamber 301 has an innerdiameter of approximately 3 inches, an outer diameter of approximately 4inches, and a height of approximately 2 inches. The soil samples thatare placed in the chamber 301 are separated from the leachate andprevented from passing through either the chamber inlet 302 or thechamber outlet 303 by the implementation of two 200 sieve stainlesssteel screens. The interior of the chamber 301 is comprised of Teflon®.The function of the chamber is to contain a sample while pressurizingthe sample to the predetermined coal tar pressures or predeterminedwater pressures as described above in method 100 discussed in connectionwith FIG. 1 and method 200 discussed in connection with FIG. 2.

It should be appreciated that chamber 301 can be a pressurizablecontainer of any size, configuration and material that will provide theintended function of the present invention. In one example, the entirestructure of the chamber 301 is stainless steel. In another example, thechamber 301 comprises acrylic components in combination with stainlesssteel structural support. In another example, the chamber 301 is capableof withstanding less than 500 psi.

The first reservoir 304 and second reservoir 307 are each a burette, andeach is pressurizable up to at least 200 psi. Each burette has an innerdiameter of approximately 0.5 inches, a height of approximately 24inches, and is translucent to allow for visually measuring the amount ofwater or coal tar displaced from a sample. The function of thereservoirs is feeding water at predetermined water pressures, feedingcoal tar at predetermined coal tar pressures, and collecting thedisplaced water and coal tar from a sample under pressure in order tomeasure the amount of water and coal tar displaced as described above inmethod 100 discussed in connection with FIG. 1 and method 200 discussedin connection with FIG. 2. To accomplish this, a manifold 301 is used todirect fluid flow from the reservoirs to the chamber inlet 302 and fromthe chamber outlet 303 back to the reservoirs. (The connection from thechamber outlet 303 to the manifold 301 is not shown.) It should beappreciated that a third reservoir 325 may alternatively be used toreceive fluid from the chamber outlet 303 for measurement.

It should be appreciated that the reservoirs can be of any size,configuration and material that will provide the intended function ofthe invention. In one example, the reservoirs are not translucent andmerely collect the water or coal tar for a gravimetric determination ofthe amount of water or coal tar displaced. In another example, thereservoirs are a combination of a translucent inner sleeve and astainless steel outer sleeve to enable the reservoirs to withstand highpressures.

For purposes of verifying the pressure at which coal tar can bedisplaced from the given type of soil, the system is comprised of thechamber 301 connected to container 311, wherein both the chamber 301 andthe container 311 are adaptable for connection to a hydrophilic filter316. The chamber 301 is connected to the container 311 by connecting thechamber outlet 303 to the container inlet 312. The hydrophilic filter316 is connected to the chamber 301 or the container 311 by connectingeither the chamber outlet 303 or the container outlet 313 to thehydrophilic filter inlet 317.

It should be appreciated that the controlled source of pressure can be asource of positive or negative pressure. As such, a controlled source ofnegative pressure 322 can be attached indirectly to the chamber outlet303. In one example, the controlled source of negative pressure isindirectly connected to the chamber outlet 303 through the containeroutlet 313. In another example, the controlled source of negativepressure 321 is indirectly connected to the chamber outlet 303 throughhydrophilic filter vacuum port 315. In another example, the controlledsource of negative pressure is indirectly connected to the chamberoutlet 303 through any other indirect connection known to one of skillin the art including, but not limited to, a trap or condenser.

A description of the chamber 301 is given above. The container 311 is acylinder that is pressurizable up to at least 200 psi. The dimensions ofthe container 311 are approximately the same as the dimensions of thechamber 301. The container may be comprised of glass. The function ofthe container 311 is to collect leachate 314 from a sample 310 that isdisplaced when pressurizing the sample 310 to the predeterminedpressures as described above in the method 300 discussed in connectionwith FIG. 3.

It should be appreciated that the container 311 can be a pressurizablecontainer of any size, configuration and material that will provide theintended function of the present invention. In one example, the entirestructure of the container 311 is stainless steel. In another example,the container 301 is acrylic. In another example, the container 311 iscapable of withstanding less than 200 psi. It should also be appreciatedthat another function of container 311 is to serve as a connection forpressurizing chamber 301 with a source of controlled negative pressure.

The hydrophilic filter 316 is a cylinder that is pressurizable to atleast 200 psi. The dimensions of the hydrophilic filter 316 areapproximately the same as the dimensions of the chamber 301 and thecontainer 311. The hydrophilic filter 316 may be comprised of glass andcontains a replaceable hydrophilic filter element 319 that is paper. Thefunction of hydrophilic filter 316 is separating components from theleachate 314 that can pass through the hydrophilic filter 316 to producesoluble leachate 320.

It should be appreciated that hydrophilic filter 316 can be apressurizable container of any size, configuration and material thatwill provide the intended function of the present invention. In oneexample, the entire structure of the hydrophilic filter 316 is stainlesssteel. In another example, the hydrophilic filter 316 is acrylic. Inanother example, the hydrophilic filter 316 is capable of withstandingless than 200 psi. In another example, the hydrophilic filter element319 is porous glass. It should also be appreciated that another functionof hydrophilic filter 316 is to serve as a connection for pressurizingchamber 301 with a source of controlled negative pressure.

The invention has been described above. The following Examples arepresented to illustrate ways of determining an amount of coal tar thatcan enter, and subsequently be displaced from, a given type of soil fora range of depths of the soil, and verifying the pressure at which coaltar can be displaced from the given type of soil, rather than to limitthe scope of the invention.

EXAMPLE I

In order to determine the concentration of components in coal tar,extraction of MAHs and PAHs from coal tar samples from 9 MGP sites wasperformed using EPA method 3580 and analyzed by GC/MS with EPA method8270, each of which are incorporated by reference herein in theirentirety. Large particles of gravel, wood, and brick were removed, andthe samples were homogenized by mixing in a stainless steel bowl. Theconcentrations of coal tar components are shown in Table 1.

TABLE 1 Concentrations at Particular Sites (mg/kg) Compounds 1 2 3 4 5 67 8 9 Benzene 48 984 491 514 523 964 986 1690 1360 Toluene 210 3690 20203100 1000 3330 2840 6370 4270 Ethylbenzene 48 2920 1330 901 251 647 17602590 3790 m/p-Zylenes 284 3120 1720 2920 1160 3020 2100 4620 3400Styrene 183 954 122 2450 467 508 1110 3410 337 0-Xylene 148 1610 7281600 440 1620 1060 2180 1590 1,2,4Trimethylbenzene 323 1950 884 1830 7052650 1130 2710 2410 Naphthalene 10000 32700 7770 20600 27500 28800 1390056100 68200 2-Methylnaphthalene 4660 19000 5270 12300 6860 27000 862024000 38300 1-Methylnaphthalene 2870 16200 3330 8900 3930 17400 553014000 24300 Acenaphthylene 1710 9520 567 4730 4050 6600 2430 8040 20000Acenaphthene 430 1880 1150 612 928 1330 559 959 2300 Dibenzofuran 15201030 185 1000 5250 1040 180 421 2505 Fluorene 2420 6320 716 2730 29604540 1370 2540 9510 Phenanthrene 5570 17300 2160 8010 10400 14200 40809830 27200 Anthracene 1670 5170 634 2780 3090 4020 1210 2970 8310Fluoranthene 2870 5240 572 2550 6220 2390 1330 3070 8690 Pyrene 21007150 762 3200 5110 4260 2200 4750 11400 Benz[a]anthracene 1110 3600 3471680 2440 1210 1020 1950 4390 Chrysene 802 3930 339 1430 2250 1080 9791840 3850 Benzo[b]fluoranthene 481 1170 136 638 1630 329 389 735 1930Benzo[k]fluoranthene 695 1650 156 712 1780 413 419 1060 2420Benzo[a]pyrene 678 2610 268 1150 2340 816 864 1960 4100Indeno[1,2,3cd]pyrene 311 797 85 371 1270 202 295 671 1530Dibenz[a,h]anthracene 94 346 34 151 366 80 124 222 463Benzo[g,h,i]perylene 351 1000 100 465 1400 251 487 898 1930

The contaminants of most interest in Table 1 are (1) MAHs including, butnot limited to, benzene, toluene, ethylbenzene, and o-xylene; (2) PAHswith two or three rings including, but not limited to, naphthalene,fluorene, anthracene, and phenthrene; and (3) PAHs with four rings orhigher including, but not limited to, fluoranthene and pyrene.

EXAMPLE 2

FIG. 6 is an example of a coal tar injection curve. It illustrates thedrainage of water and the imbibition of coal tar. In this case theresidual saturation of coal tar is approximately at 18% and 5000 mm Hg.

While the foregoing description and drawings represent the preferredembodiments of the present invention, it will be understood that variousadditions, modifications and substitutions may be made therein withoutdeparting from the spirit and scope of the present invention as definedin the accompanying claims. In particular, it will be clear to thoseskilled in the art that the present invention may be embodied in otherspecific forms, structures, arrangements, proportions, and with otherelements, materials, and components, without departing from the spiritor essential characteristics thereof. The presently disclosedembodiments are, therefore, to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims, and not limited to the foregoingdescription.

For example, the invention has been described above using a positivepressure such as compressed air to pressurize the chamber and feed waterand coal tar into soil samples, whereas other forms of pressure may beused. In one example, a mechanical positive pressure, such as a press,may be used. In another example, a vacuum may be used. Moreover,although the invention has been described as using a particular numberor shape of system components, it is to be understood that othercomponents may be used with the system and method of the presentinvention. For example, the chamber may be cylindrical, square,rectangular, or any shape that allows for pressurizing a sample todisplace leachate from soil. Further, it should be appreciated thatmultiple chambers may be used simultaneously along with multiplereservoirs, multiple containers and multiple filters.

1. An apparatus, adaptable for positioning in the laboratory or thefield, for determining an amount of coal tar that can enter, andsubsequently be displaced from, a given type of soil for a range ofdepths of the soil, comprising: a pressurizable chamber configured tohold a soil sample; at least two reservoirs fluidly connected to saidpressurizable chamber and configured to feed a pressurized fluid to saidpressurizable chamber; and a source of controlled pressure fluidlyconnected to each of said at least two reservoirs.
 2. The apparatus ofclaim 1, further comprising: a container fluidly connected to saidchamber for collecting leachate from the soil sample in said chamber; ahydrophilic filter fluidly connected to said container.